1. Field of the Invention
The present invention relates to a backlight assembly and a display device including the same, and more particularly to a backlight assembly in which heat dissipation performance is enhanced and its structure is simplified, and to a display device including the same.
2. Description of the Related Art
Recently, in order to reduce the use of energy and decrease the greenhouse gas to promote low-carbon green growth all over the world, light emitting diodes (LEDs) which are regarded as a low-pollution eco-friendly product are being increasingly used as a backlight in a variety of liquid crystal displays.
A display device (e.g. a liquid crystal display (LCD)) is the type of flat panel display (FPD) that is the most widely used these days, and is configured such that a liquid crystal layer is interposed between two substrates having electrodes, so that liquid crystal molecules of the liquid crystal layer are rearranged upon applying voltage to the electrodes, thereby adjusting the amount of transmitted light.
A display device which is a passive light emitting device includes a display panel for displaying an image and a backlight assembly which supplies light to the display panel. The backlight assembly is classified as a direct type or an edge type depending on the position of a light source.
The demand for display devices which are light, slim, short and small and are improved in color reproducibility is recently increasing. Accordingly, research into using a point light source such as an LED (Light Emitted Diode) as a light source provided in the backlight assembly is ongoing. In particular, to increase performance of the display device and prevent the light source from deteriorating, enhancement of heat dissipation performance is essential.
Hence, in consideration of high efficiency, high integration, high functionality and the fabrication of light, slim, short and small devices in the industry, LEDs are designed in the form of a part, a module, a set, etc. When designers of respective fields make their designs so that they satisfy the above mentioned technical trends, there may occur cases where more heat may be generated compared to that generated by conventional design techniques, undesirably causing problems of the performance of the system or the like deteriorating due to such heat. Accordingly in the related industrial fields, thorough research into efficiently solving thermal problems (i.e. heat dissipation, heat diffusion, heat dispersion, heat collection, heat transfer, etc.) of generated heat continues.
A backlight using an LED includes an LED device having high energy efficiency, a power stabilization device which stabilizes power supplied to the LED element, and a heat dissipation member which dissipates heat generated from the above two devices to the atmosphere.
When the LED which is a compound semiconductor is used at higher temperature, thermal vibration of atoms obstructs the flow of electrons, undesirably lowering illuminance. As the temperature becomes very high, diffusion occurs in the diffusion layer of the semiconductor, drastically lowering illuminance and remarkably shortening the service life.
The case where the power stabilization device is unstable creates an electrical impact on the LED, and upon AC/DC conversion of the power stabilization device, a large amount of heat is generated and thus performance of the semiconductor of the power stabilization device may deteriorate upon driving at high temperature, undesirably shortening the lifetime of the backlight for a liquid crystal display.
Also a backlight for a liquid crystal display needs to be prepared to be dust-proof and explosion-proof as well as waterproof depending on the operating environment.
Useful in a conventional LED is a heat dissipation material that is a metal having high thermal conductivity, for example, copper or aluminum. Typically it is known that copper has a thermal conductivity of 300 W/mk and aluminum has a thermal conductivity of 175 W/mk, and these metals are thermally and electrically conductive because of metal bonding. However, the heat and electricity conduction directions are isotropic because of free electrons and thermal and electrical conductivities may decrease due to thermal vibration of lattices at high temperature, and heat emitted from a heat source may dissipate only by means of isotropic heat diffusion when using a heat dissipation member made of a metal, thus forming a temperature distribution such as hot spots, undesirably resulting in deteriorated heat dissipation effects. In order to solve such problems, a heat sink of copper or aluminum having fast heat diffusion may be formed to be thick or its surface area may be increased, thus increasing the contact surface with a convective surface (air or water), or grooves may be made on the surface of the heat sink in a vertical direction. In this case, however, the heat sink has a complex shape and becomes heavy and the manufacturing process becomes complicated. Moreover, because metal resources are limited, they are expensive and their supply may not be efficient depending on the international situation, and a lot of energy is consumed upon ore smelting.